Clear the last of the nil checks

Guards now cover the statements that follow them, and a couple of reads
are restructured so the narrowing survives.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

exp_commands/module/commands/help.lua

@@ -71,7 +71,7 @@ Commands.new("commands", { "exp-commands_help.description" })
             page = as_number
         end
 
-        keyword = assert(keyword):lower()
+        keyword = tostring(keyword):lower()
         local pages, found
         if cache and cache.keyword == keyword then
             -- Cached value found, no search is needed

exp_legacy/module/expcore/external.lua

@@ -14,7 +14,8 @@ end
 
 ]]
 
-local ext, var
+local ext --- @type table<string, any>
+local var --- @type table<string, any>
 local concat = table.concat
 
 local External = {}
@@ -29,12 +30,13 @@ end
 
 ]]
 function External.valid()
-    if storage.ext == nil then return false end
+    local stored = storage.ext
-    if ext == storage.ext and var == ext.var then
+    if stored == nil then return false end
+    if ext == stored and var == ext.var then
         return var ~= nil
     else
-        ext = storage.ext
+        ext = stored
-        var = ext.var
+        var = stored.var
         return var ~= nil
     end
 end

exp_legacy/module/modules/control/protection.lua

@@ -34,7 +34,7 @@ for _, config_key in ipairs{ "always_protected_names", "always_protected_types",
 end
 
 -- Require roles if a permission is assigned in the config
-local Roles
+local Roles --- @type table<string, any>
 if config.ignore_permission then
     Roles = require("modules.exp_legacy.expcore.roles") --- @dep expcore.roles
 end

exp_legacy/module/modules/control/spectate.lua

@@ -4,7 +4,7 @@ local Gui = require("modules/exp_gui")
 local Event = require("modules/exp_legacy/utils/event") --- @dep utils.event
 
 ----- Locals -----
-local follow_label -- Gui constructor
+local follow_label --- @type ExpElement Gui constructor
 local following = {}
 local spectating = {}
 local Public = {}

exp_legacy/module/modules/gui/warp-list.lua

@@ -673,7 +673,7 @@ warp_list_container = Gui.define("warp_list_container")
         -- Draw the scroll table for the warps
         local scroll_table = Gui.elements.scroll_table(container, 250, 3, "scroll")
         -- Set the scroll panel to always show the scrollbar (not doing this will result in a changing gui size)
-        scroll_table.parent.vertical_scroll_policy = "always"
+        assert(scroll_table.parent).vertical_scroll_policy = "always"
 
         -- Change the style of the scroll table
         local scroll_table_style = scroll_table.style
@@ -874,7 +874,7 @@ local function role_update_event(event)
     -- Check if user has permission to add warps
     local allow_add_warp = check_player_permissions(player, "allow_add_warp")
     -- Update container size depending on whether the player is allowed to add warps
-    frame.parent.style.width = allow_add_warp and 268 or 220
+    assert(frame.parent).style.width = allow_add_warp and 268 or 220
 
     -- Update the warps, in case the user can now edit them
     local scroll_table = frame.scroll.table

exp_scenario/module/control/spawn_area.lua

@@ -149,13 +149,15 @@ local function create_entities(surface, offset)
         local pos = apply_offset({ entity_details[2], entity_details[3] }, offset)
         local entity = surface.create_entity{ name = entity_details[1], position = pos, force = "neutral" }
 
-        if entity and config.entities.protected then
+        if entity then
+            if config.entities.protected then
                 protect_entity(entity)
             end
 
             entity.operable = config.entities.operable
         end
     end
+end
 
 --- Generates an area with no water or entities, no water area is larger
 --- @param surface LuaSurface
@@ -276,7 +278,8 @@ local function on_player_created(event)
     if config.resource_patches.enabled then create_resource_patches(surface, offset) end
     if config.turrets.enabled then update_turrets() end
 
-    (player.force --[[@as LuaForce]]).set_spawn_position(offset, surface)
+    local force = player.force --[[@as LuaForce]]
+    force.set_spawn_position(offset, surface)
     player.teleport(offset, surface)
 end
 

exp_scenario/module/gui/player_list.lua

@@ -106,7 +106,7 @@ Elements.reason_confirm = Gui.define("player_list/reason_confirm")
             if reason == nil or not reason:find("%S") then reason = "no reason given" end
             button_data.reason_callback(player, reason)
         end
-        element.parent.entry.text = ""
+        assert(assert(element.parent).entry).text = ""
         Elements.container.set_selected_player(player, nil)
         Elements.player_table.refresh_player(player)
     end) --[[@as any]]

exp_scenario/module/gui/science_production.lua

@@ -193,7 +193,8 @@ Elements.science_table = Gui.define("science_production/science_table")
         local science_table = Gui.elements.scroll_table(parent, 190, 4)
         local no_production_label = Elements.no_production_label(science_table)
         Elements.no_production_label.refresh(no_production_label)
-        (science_table.style --[[@as LuaStyle]]).column_alignments[3] = "right"
+        local science_table_style = science_table.style --[[@as LuaStyle]]
+        science_table_style.column_alignments[3] = "right"
         return science_table
     end) 
     :element_data{} --[[@as any]]
@@ -280,7 +281,8 @@ function Elements.science_table.add_row(science_table, row_data)
         column_count = 2,
     }
     delta_table.style.padding = 0
-    (delta_table.style --[[@as LuaStyle]]).column_alignments[1] = "right"
+    local delta_table_style = delta_table.style --[[@as LuaStyle]]
+    delta_table_style.column_alignments[1] = "right"
 
     -- Draw the net production label
     local net = Elements.production_label(science_table, row_data.net)
@@ -429,11 +431,13 @@ do local _display_data = {} --- @type table<string, Elements.eta_label.display_d
         -- Update the eta labels
         for player, eta_label in Elements.eta_label:online_elements() do
             local display_data = _display_data[player.force.name]
+            if display_data then
                 eta_label.caption = display_data.caption
                 eta_label.tooltip = display_data.tooltip
             end
         end
     end
+end
 
 --- Container added to the left gui flow
 --- @class ExpGui_ScienceProduction.elements.container: ExpElement